RESUMEN
Thermogenic brown adipose tissue (BAT) has emerged as an attractive target for combating obesity. However, pharmacological activation of energy expenditure by BAT and/or induction of browning of white adipose tissue (WAT) has been hampered by cardiovascular side effects. To address these concerns, we developed polylactide-co-glycolide acid (PLGA) microspheres loaded with mirabegron (MIR), a selective beta-3 adrenergic receptor (ADRB3) agonist, to achieve sustained local induction and activation of thermogenic adipocytes. MIR-loaded PLGA microspheres (MIR-MS) effectively activated brown adipocytes and enhanced the thermogenic program in white adipocytes. Moreover, treating isolated inguinal WAT (iWAT) with MIR-MS resulted in increased expression of browning markers and elevated lipolysis mainly via ADRB3. In mice, injection of MIR-MS over four weeks induced browning of iWAT at the injection site. Importantly, local MIR-MS injection successfully mitigated unwanted cardiovascular risks, including high systolic blood pressure (SBP) and heart rate, as compared to MIR-treated mice. Finally, injecting MIR-MS into human subcutaneous WAT led to a significant induction of lipolysis and an increase in the expression of thermogenic marker uncoupling protein 1 (UCP1). Taken together, our findings indicate that MIR-MS function as a local drug release system that induces browning of human and murine subcutaneous WAT while mitigating undesirable cardiovascular effects.
RESUMEN
Spray drying is one of the most frequently used solvent-based processes for manufacturing amorphous solid dispersions (ASDs). However, the resulting fine powders usually require further downstream processing when intended for solid oral dosage forms. In this study, we compare properties and performance of spray-dried ASDs with ASDs coated onto neutral starter pellets in mini-scale. We successfully prepared binary ASDs with a drug load of 20% Ketoconazole (KCZ) or Loratadine (LRD) as weakly basic model drugs and hydroxypropyl-methyl-cellulose acetate succinate or methacrylic acid ethacrylate copolymer as pH-dependent soluble polymers. All KCZ/ and LRD/polymer mixtures formed single-phased ASDs, as indicated by differential scanning calorimetry, X-ray powder diffraction and infrared spectroscopy. All ASDs showed physical stability for 6 months at 25 °C/65% rH and 40 °C/0% rH. Normalized to their initial surface area available to the dissolution medium, all ASDs showed a linear relationship of surface area and solubility enhancement, both in terms of supersaturation of solubility and initial dissolution rate, regardless of the manufacturing process. With similar performance and stability, processing of ASD pellets showed the advantages of a superior yield (>98%), ready to use for subsequent processing into multiple unit pellet systems. Therefore, ASD-layered pellets are an attractive alternative in ASD-formulation, especially in early formulation development at limited availability of drug substance.
RESUMEN
Ungual formulations are regularly tested using human nails or animal surrogates in Franz diffusion cell experiments. Membranes sometimes less than 100 µm thick are used, disregarding the higher physiological thickness of human nails and possible fungal infection. In this study, bovine hoof membranes, healthy or infected with Trichophyton rubrum, underwent different imaging techniques highlighting that continuous pores traversed the entire membrane and infection resulted in fungal growth, both superficial, as well as in the membrane's matrix. These membrane characteristics resulted in substantial differences in the permeation of the antifungal model substance bifonazole, depending on the dosage forms. Increasing the thickness of healthy membranes from 100 µm to 400 µm disproportionally reduced the permeated amount of bifonazole from the liquid and semisolid forms and allowed for a more pronounced assessment of the effects by excipients, such as urea as the permeation enhancer. Similarly, an infection of 400-µm membranes drastically increased the permeated amount. Therefore, the thickness and infection statuses of the membranes in the permeation experiments were essential for a differential readout, and standardized formulation-dependent experimental setups would be highly beneficial.
